Physical Science 101
Weather vs. Climate
Weather – current state of the atmosphere
Climate – aggregate atmospheric conditions; long-term average weather
How do we measure global temperature?
What is the problem with using thermometers for measuring long term average temperature?
Limited span of time: first thermometer invented:
Average of all temperature record measurements. Historical records Municipal/state/federal records Amateur records and diaries How do we get data from before 1611?
Proxy Temperature Records
Data from sources which do not give actual temp. – provide an inferred temperature
Biological Proxy Records: tree rings, pollen, floral and faunal distributions, fossils
Geological Proxy Records: sediment/glacial deposits, ice cores, minerals, geochemistry
Chemical Proxy Records: O18/O16 ratios (ice and foram shells)
Sea level is not constant
Changes on a daily basis:
Changes on an annual basis:
Causes of eustatic changes in sea level:
Is the world actually getting warmer?
“Warming of the climate system is unequivocal… The atmosphere and oceans have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentration of greenhouse gases have increased.” – IPCC 2013: Climate Change 2013: The Physical Science Basis.
The Evidence of Global Warming
Ten Signs of a Warming World - NOAA web site
The Evidence - Summary
Causes of Climate Change
Natural Causes or Human Induced Causes?
Main energy source at Earth's surface.
Driving force for:
Changes in amounts of incoming vs. outgoing radiation will result in global warming or cooling.
Factors controlling amount of insolation:
Surface insolation variations due to orbital parameter variations.
1) Axial tilt
3) Orbital Eccentricity
A system in which shortwave radiation is allowed to enter freely and is absorbed, then is re-radiated as longwave radiation. The longwave radiation is then retained within the system.
Important greenhouse gases:
CO2 Carbon Dioxide
Nitrous oxide (N2O)